Im up to 6 million gold in AH sales (about 1-2 million profit).

Because alchemy can generate you passive income, via a daily transmute.
You might benefit from one Blacksmith, Enchanter, Jewelcrafter, Leatherworker, Scribe, Tailor etc, across your teams.
Ya thats the best.

Most of my money came from darkmoon trinket sales but as that has dried up and I had like 400K I bought a lot of essesne of distruction and made the 3 plate legs and the cloth damage legs (the 397 ones). I kinda lost a bit as I bought 40 or so essense at 8K and the market is down to 3K now. But I did make some sales at the high level so hopefully I wont lose to much.

Its really hard to come up with one "best" method as things are alwasy changing.

I bought 30 queens garnets at 2.8K each but have not sold a single cut one at 4.9K but sold 2 uncut at 4.5K .... go figure.

Once you have a lot of gold I think you just chase the big ticket items, but dont buy to soon like I did.

I started with bags, you cant go wrong there.

I used to mill like 2 hours a night while watching movies for the darkmoon card but now I am so lazy I just buy the inferno inks (and have have over 200 trinkets in the bank anyway).